Debate about the origins of syphilis has continued for nearly 500 years, ever since early sixteenth-century Europeans blamed each other, referring to it variously as the Venetian, Naples, or French disease. One hypothesis assumes a New World origin, and holds that sailors who accompanied Columbus and other explorers brought the disease back to Europe. Another explanation is that syphilis was always present in the Old World but was not identified as a separate disease from leprosy before about A.D. 1500. A third possibility is that syphilis developed in both hemispheres from the related diseases bejel and yaws. New studies by paleopathologists Bruce and Christine Rothschild favor a New World origin.

Ancient and medieval sources have long been cited as evidence for syphilis in Europe before Columbus, but none of the descriptions by Greek and Roman authors are specific enough to be certain. Returning crusaders brought "Saracen ointment" containing mercury for treating "lepers," an appropriate medication for syphilis but not for leprosy. Thirteenth- and fourteenth-century A.D. references to "venereal leprosy" may also indicate syphilis because leprosy is not sexually transmitted. But the first unambiguous descriptions of syphilis begin around 1500. These may either reflect growing medical knowledge and ability to differentiate syphilis from other diseases or signal its arrival from the New World.

Syphilis is caused by the bacterium Treponema palladium; other bacteria in the same genus cause yaws and bejel, which are transmitted through direct skin-to-skin contact or sharing of drinking vessels. Like syphilis, bejel and yaws cause inflammation of tissue surrounding bone and modify the bones. To establish criteria for distinguishing among the three diseases based on skeletal changes the Rothschilds analyzed a North American collection of skeletons for syphilis cases (diagnosed at autopsy), a collection from Guam predating 1668 for yaws (the only treponemal disease on the island before then), and early historic Near Eastern Bedouin for bejel (bejel is endemic to the region). They were able to identify characteristic bone changes for each disease, for example, modifications to the shin and tibia particular to syphilis, or routine involvement of hand or foot in yaws but not syphilis or bejel.

Using these criteria, they examined 687 skeletons from archaeological sites in the United States and Ecuador ranging in age from 400 to 6,000 years. Populations to the south (New Mexico, Florida, and Ecuador) proved to have syphilis, while those to the north (Ohio, Illinois, and Virginia) had yaws. By contrast, examination of 1,000 Old World skeletons dated to before contact with the New World revealed no cases of syphilis. This suggests that syphilis was first present in the New World and was later brought to the Old World. Furthermore, the Rothschilds found that the earliest yaws cases in the New World collections were at least 6,000 years old, while the first syphilis cases were at least 800 years old and perhaps more than 1,600 years old. This suggests that syphilis may be a New World mutation of yaws, which has a worldwide distribution. The occurrence of the same mutation giving rise to syphilis independently in the New and Old worlds seems unlikely.

Identification of syphilis on an Old World skeleton predating Columbus would be strong evidence that the disease either originated in the Old World or occurred in both hemispheres. Olivier Dutour of the Faculty of Medicine at Marseilles has recently concluded that the skeleton of a seven-month-old fetus found in a fouth-century A.D. context at Costebelle, France, had lesions from congenital syphilis. But Bruce Rothschild, who has examined the Costebelle skeleton, contends that it is not a case of congenital syphilis but of lithopedion. "Stone children" or lithopedion, a rarity occurring in only 0.0045 percent of pregnancies, are the calcification of a fetus or of fetal membranes and were first described in a treatise on surgery by Albucasis (A.D. 936-1013). The Rothschilds and University of Texas at Austin archaeologist Leland Bement have recently identified a 3,100-year-old lithopedion case at the Bering Sinkhole site in Texas.

According to Bruce Rothschild the lesions in the Costebelle case indicate lithopedion. "The character of the pathology appeared to me to be calcified membranes/tissues, rather than periosteal reaction," he says. "The skull lesions are unlike those of treponemal disease (e.g., congenital syphilis) and the dramatic forearm calcification is unlike anything we have previously witnessed in over 500 cases of adult syphilis, nor in the periosteal reaction that characterizes yaws and bejel--disorders in which children (though probably not fetuses) are frequently affected."

Syphilis, it seems, developed in the New World from yaws, perhaps 1,600 years ago, and was waiting for Columbus and his crew. The Rothschilds are now examining skeletal collections from the Bahamas to look for evidence of syphilis nearer to Columbus' landfall.